No one will tell you.
I had 680i ASUS board with 4x 2GB Supertalent memory, based on Micron D9HNL, running DDR2-667@800 no problem (except very low memory performance, thats why i switched to P35).

You have two options : try to test on P35/X38 board. If you don't have/need SLI, i highly recommend you make this switch anyway.
Or try another pair of sets.

By the way, make sure your tRFC is right, should be 52+ for DDR2-1000 speed.